/* ls2.c
 * purpose list contents of directory or directories
 * action if no args, use . else list files in args
 * note uses stat and pwd.h and grp.h
 * BUG: try ls2 /tmp
 */
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <string.h>

void do_ls(char[]);
void dostat(char *);
void show_file_info(char *, struct stat *);
void mode_to_letters(int,  char[]);
char * uid_to_name(uid_t);
char * gid_to_name(gid_t);

main(int ac, char * av[])
{
	if (ac == 1)
		do_ls(".");
	else
		while( --ac )
		{
			printf("%s:\n", *++av);
			do_ls( *av );
		}
}

void do_ls(char dirname[])
/*
 * list files in directory called dirname
 */
{
	DIR *dir_ptr;			/* the directory */
	struct dirent * direntp;	/* each entry */

	if ((dir_ptr = opendir( dirname )) == NULL)
		fprintf(stderr, "ls1:cannot open %s\n", dirname);
	else
	{
		while ((direntp = readdir(dir_ptr)) != NULL)
			dostat(direntp->d_name);
		closedir(dir_ptr);
	}
}

void dostat(char * filename)
{
	struct stat info;

	if(stat(filename, &info) == -1)		/* cannot stat */
		perror(filename);		/* say why */
	else					/* else show info */
		show_file_info(filename, &info);
}

void show_file_info(char * filename, struct stat * info_p)
/*
 * display the info about filename. The info is stored in struct at * info_p
 */
{
	char *uid_to_name(), *ctime(), *gid_to_name(), *filemode();
	void mode_to_letters();
	char modestr[11];

	mode_to_letters(info_p->st_mode, modestr);

	printf(" %s ", modestr);
	printf(" %4d ", (int)info_p->st_nlink);
	printf(" % -8s ", uid_to_name(info_p->st_uid));
	printf(" % -8s ", gid_to_name(info_p->st_gid));
	printf(" %8ld ", (long)info_p->st_size);
	printf(" % .12s ", 4 + ctime(&info_p->st_mtime));
	printf(" %s\n", filename);
}

/*
 * utility functions
 */

/*
 * This function takes a mode value and a char array
 * and puts into the char array the file type and the
 * nine letters that correspond to the bits in mode.
 * NOTE: It does not code setuid, setgid, and sticky
 * codes
 */
void mode_to_letters(int mode, char str[])
{
	strcpy(str, "---------------");		/* default=no perms */

	if (S_ISDIR(mode)) str[0] = 'd';	/* directory? */
	if (S_ISCHR(mode)) str[0] = 'c';	/* char devices */
	if (S_ISBLK(mode)) str[0] = 'b';	/* block device */

	if (mode & S_IRUSR) str[1] = 'r';	/* 3 bits for user */
	if (mode & S_IWUSR) str[2] = 'w';
	if (mode & S_IXUSR) str[3] = 'x';

	if (mode & S_IRGRP) str[4] = 'r';	/* 3 bits for group */
	if (mode & S_IWGRP) str[5] = 'w';
	if (mode & S_IXGRP) str[6] = 'x';

	if (mode & S_IROTH) str[7] = 'r';	/* 3 bits for other */
	if (mode & S_IWOTH) str[8] = 'w';
	if (mode & S_IXOTH) str[9] = 'x';
}

#include <pwd.h>

char * uid_to_name(uid_t uid)
/*
 * returns pointer to username associated with uid, uses getpw()
 */
{
	struct passwd * getpwuid(), * pw_ptr;
	static char numstr[10];

	if ((pw_ptr = getpwuid(uid)) == NULL)
	{
		sprintf(numstr, "%d", uid);
		return numstr;
	}
	else
		return pw_ptr->pw_name;
}

#include <grp.h>

char * gid_to_name(gid_t gid)
/*
 * returns pointer to group number gid. used getgrgid(3)
 */
{
	struct group * getgrgid(), * grp_ptr;
	static char numstr[10];

	if ((grp_ptr = getgrgid(gid)) == NULL)
	{
		sprintf(numstr, "%d", gid);
		return numstr;
	}
	else
		return grp_ptr->gr_name;
}
